Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
OPERATING ACTIVITIES
Net income	$ 310,840	$ 269,345
Adjustments to reconcile net income to cash provided by operating activities:
Provision (credit) for loan and lease losses	16,883	28,501
Deferred tax expense (benefit)	13,642	67,270
Net change in current taxes	(21,266)	17,115
Depreciation	71,484	67,749
Net (decrease) increase in accrued interest payable	(1,552)	401
Net (increase) decrease in income earned not collected	(7,650)	(4,471)
Gain on acquisitions	0	(134,745)
Securities (gains) losses, net	0	(4,664)
Marketable equity securities gain (loss), net	(9,265)	0
Gain on extinguishment of debt	(26,517)	0
Origination of loans held for sale	(456,193)	(471,862)
Proceeds from sale of loans held for sale	468,705	487,017
Gain on sale of loans held for sale	(8,640)	(11,317)
(Gain) loss on sale of portfolio loans	0	(1,007)
Net writedowns/losses on other real estate	3,156	3,152
(Gain) loss on sales of premises and equipment	(1,450)	(490)
Net accretion of premiums and discounts	(22,965)	(34,535)
Amortization of intangible assets	17,580	16,994
Net change in FDIC receivable for shared-loss agreements	0	5,799
Net change in FDIC payable for shared-loss agreements	3,234	3,195
Net change in other assets	339,289	(9,521)
Net change in other liabilities	(53,708)	10,178
Net cash provided by operating activities	635,607	304,104
INVESTING ACTIVITIES
Net increase in loans outstanding	(702,356)	(771,593)
Purchases of investment securities available for sale	(979,495)	(1,891,967)
Purchases of investment securities held to maturity	(68,699)	0
Purchases of marketable equity securities	(2,818)	0
Proceeds from maturities/calls of investment securities held to maturity	196,146	20
Proceeds from maturities/calls of investment securities available for sale	946,293	1,436,113
Proceeds from sales of investment securities available for sale	119,273	538,317
Proceeds from sales of marketable equity securities	9,503	0
Net decrease (increase) in overnight investments	455,295	(458,027)
Proceeds from sales of portfolio loans	0	162,486
Cash paid to the FDIC for shared-loss agreements	0	(7,440)
Net payment to the FDIC for termination of shared-loss agreements	0	(285)
Proceeds from sales of other real estate	23,488	31,072
Proceeds from sales of premises and equipment	1,648	2,920
Purchases of premises and equipment	(88,270)	(60,090)
Net cash acquired in business acquisitions	(106,298)	300,703
Net cash used in investing activities	(196,290)	(717,771)
FINANCING ACTIVITIES
Net decrease in time deposits	(218,826)	(469,540)
Net increase in demand and other interest-bearing deposits	496,499	538,084
Net decrease in short-term borrowings	(127,547)	(59,207)
Repayment of long-term obligations	(717,370)	(6,819)
Origination of long-term obligations	125,000	175,000
Repurchase of common stock	(58,086)	0
Cash dividends paid	(12,612)	(7,206)
Net cash (used in) provided by financing activities	(512,942)	170,312
Change in cash and due from banks	(73,625)	(243,355)
Cash and due from banks at beginning of period	336,150	539,741
Cash and due from banks at end of period	262,525	296,386
SUPPLEMENTAL DISCLOSURE OF NONCASH INVESTING AND FINANCING ACTIVITIES:
Transfers of loans to other real estate	17,013	26,926
Dividends declared but not paid	4,168	3,603
Transfer of Loans Held-for-sale to Portfolio Loans	2,016
Transfer of Portfolio Loans and Leases to Held-for-sale		161,719
Transfer of investment securities available for sale to held to maturity	$ 2,485,761	$ 0